Manufacturing is becoming more effecient, therefor presently employs less people, much the same happened to agriculture. And people should not interpret that as a portent of a falling economy, and try to remedy it. Agriculture produces and markets more now than it ever has, yet a relatively small fraction of the population are employed in the agriculture industry. We didn't miss the point.
But agriculture and manufacturing will both continue to be fields integral to human expansion. And both industries will continue to grow. Can you imagine what agriculture, manufacturing and civil engineering will be like when/if interplanetary colonization begins.